Master cylinders, old and new

[xwhatsit]

Wei wei,

Went and bought an impact driver today, as I have a few rusty screws and seized this and that on the RS. Picked up some brake fluid as well, as the front brakes look a little low on hydraulic fluid.

The master cylinder cover, held in by four screws, did look a little rusty, so I took the impact driver straight to it. Got two screws off, but the two other diagonal ones are stuck as stuck can be. All the impact driver does is gouge the heads out of them.

I could drill them out, but I do have a spare master cylinder. The brake light switch in my existing master cylinder is pretty fucked, and is araldited up; the brake light switch in the spare master cylinder (from the domestic Japan model) is a different design, and I was able to dismantle and recondition it quite well (green copper, yuck) until it worked on the multimeter.

Now, ideally I'd love to stick a TLS drum on the front, but every time I mention this everybody flames me, apart from old miscreants like Ixion.So, I need to know whether my ancient spare master cylinder would be a good idea to put on. It has been sitting in a box, away from hydraulic fluid for a good 15-20 years; do seals and stuff dry out and stop doing their job? I pumped some tap water through it, it didn't seem to leak from anywhere and made a wonderful high-pressure spray when I held my thumb over the end.

Do I need to recondition this with new bits and bobs, or can I stick it straight on and just bleed the lines?

[Mental Trousers]

Just drill the 2 screws out and get some new ones. They're not exactly rare.
If the other master cylinder has been sitting around that long chances are very good that you'll ride down the road for a while, brakes working fine ..... and then not working at all with brake fluid all over your glove, tank, fairings etc.

[xwhatsit]

That's shite. Went and looked at the spare, and the little rubbery thing that the lever squeezes when you pull it looks a little bit cracked and dry.

I hate drilling stuff out, lol. Time to call up my Uncle

[dhunt]

Have you tried just a decent phillips screwdriver? What you do is put downward pressure on the screwdriver and tap the handle with a hammer at the same time you twist it. This is what I've done in the past and doesn't damage it like impact driver does.

[Kickaha]

Now, ideally I'd love to stick a TLS drum on the front, but every time I mention this everybody flames me, apart from old miscreants like Ixion.

They probably can't understand why you'd want to fit worse brakes

Once you drill the head off if there's enough thread left poking up you can quite often wind the remains of the bolt out with pliers rather than drill out the whole screw

[xwhatsit]

They probably can't understand why you'd want to fit worse brakes

That's a matter of opinion

I do have a decent phillips screwdriver, and that makes no difference -- have been employing the hammer-tap method for a while before I bought the impact driver. It really does seem seized and rusted in there.

Also, one of the screws I took out now just seems loose in there. It's not like it's threaded -- there seems to be no thread whatsoever, just an empty hole?! Good lord. At least it's not a load-bearing part or anything.

I suspect my existing master cylinder is probably partially shagged in terms of seals and such things anyway -- can you buy kits with new pistons/seals the like? Might be worth doing anyway, on either of the master cylinders I've got.

[imdying]

That's a matter of opinion

No, it would be quantifiably worse.

[xwhatsit]

Got a bigger hammer today onto the impact driver, and perhaps the cold weather helped too. Off came the lid, bled the brakes, more powerful now. Put some anti-seize onto the threads, too. Can squeal the front tyre at least, albeit it was a damp road.

Still feel very `hydraulic-y'. Is there a reason they don't make cable-operated front discs? On every bike I've ridden with hydraulic disc brakes, there's no feel whatsoever. It's not a linear feeling. Don't know quite how to describe it. I want to feel directly connected to the front brakes. The big BMW twin with drum front had that feel (couldn't feel much else though ).

[Kickaha]

Is there a reason they don't make cable-operated front discs?

Yes, because they're crap, they used to used them on small commuter bikes like the CB125T

On every bike I've ridden with hydraulic disc brakes, there's no feel whatsoever. It's not a linear feeling. Don't know quite how to describe it. I want to feel directly connected to the front brakes.

Have you tried some different m/c sizes to get the "feel" you want?

Generally on the bikes I've ridden with no feel at the lever the m/c have been to big.

[vagrant]

can you buy kits with new pistons/seals the like? Might be worth doing anyway, on either of the master cylinders I've got.

Yes you can. Honda sell them as a kit, new piston, seals and dust cap. Also a return spring and circlip to hold it all together.

[imdying]

I wouldn't, the bores will almost certainly be shagged. Send them to Apex in Hamilton and let them sort them out.